1. Field of the Invention
The present invention relates to an image forming apparatus such as electrophotographic copiers and printers. Particularly, the invention relates to an image forming apparatus including in its apparatus body: an image carrier on which an electrostatic latent image is formed; and a rotary-type development unit being rotatable about an axis thereof and having a plurality of developing devices, which are used for developing the latent images formed on the image carrier.
2. Description of the Related Art
The image forming apparatus, such as the copiers and printers, generally forms images as follows. As shown in FIG. 1, an image carrier 1 shaped like a drum and disposed in an apparatus body 10 is rotated, while a surface of the image carrier 1 is charged by means of a charger unit 2. Subsequently, the image carrier 1 thus charged is exposed to light from an exposure unit 3 according to an image signal, whereby an electrostatic latent image is formed on the surface of the image carrier 1.
Next, a development unit 4 supplies a toner to the surface of the image carrier 1 with the electrostatic latent image formed thereon, thereby forming a toner image on the surface of the image carrier 1. The toner image is transferred to a recording sheet 6 by means of a transfer unit 5. Then, the recording sheet 6 with the toner image transferred thereto is transported to a fixing unit 7, which fixes the toner image to the recording sheet 6. On the other hand, the toner remaining on the surface of the image carrier 1 after the toner image transfer is removed from the surface of the image carrier 1 by means of a cleaner 8.
In a case where the apparatus carries out the image formation as described above, the apparatus encounters a problem that the exposure unit 3 and the like disposed in the apparatus body 10 generate heat to raise temperatures in the apparatus body 10. There is another problem that ozone is released when the charger unit 2 charges the surface of the image carrier 1 and hence, the ozone is accumulated in the apparatus body 10.
In this connection, the following proposal has been made in the prior art. That is, the aforementioned image forming apparatus is provided with an air exhaust such as a fan, which is operated for forcibly discharging the heat, ozone and such generated in the apparatus body out of the apparatus body (see Japanese Unexamined Patent Publication No. 2003-280494).
However, if the image forming apparatus is provided with the air exhaust for forcibly discharging the heat, ozone and such generated in the apparatus body out of the apparatus body, the apparatus suffers disadvantages of increased size and increased running cost.
More recently, an image forming apparatus employing a rotary-type development unit 40 is used as an apparatus for forming full color images, the rotary-type development unit including plural developing devices 4A to 4D containing toners of different colors and retained by a rotatable support body 41, as shown in FIG. 2.
In this image forming apparatus, the rotary-type development unit 40 is rotated by means of the support body 41 so as to shift the developing devices 4A to 4D, in turn, to position opposite the image carrier 1. The developing devices 4A to 4D in turn supply the toners of the individual colors to the image carrier 1. The toners thus supplied to the image carrier 1 are sequentially transferred to an intermediate transfer belt 9, so that a full-colored toner image is formed on the intermediate transfer belt 9.
Subsequently, the full-colored toner image is transferred from the intermediate transfer belt 9 to the recording sheet 6, such as recording paper, by means of the transfer unit 5. The full-colored toner image so transferred is fixed to the recording sheet 6 by means of the fixing unit 7.
Unfortunately, in a case where the image forming apparatus for forming the full color image is provided with the air exhaust for forcibly discharging the heat, ozone and such generated in the apparatus body out of the apparatus body, the apparatus is further increased in size.